Field of the Invention
The present invention relates to a recording head having a recording element substrate having recording elements for use in recording on a recording medium and a driving element substrate with driving elements for driving said recording elements in accordance with an electrical signal entered from the outside, a recording apparatus provided with said recording head, and a manufacturing method thereof.
A recording element unit (recording unit) for use in an ink-jet recording apparatus is well known, for example, such as that shown in FIG. 1. In FIG. 1, a recording element substrate 101 formed with a plurality of recording elements for recording on a recording medium is joined together with a driving element substrate 106 formed with driving elements 107 for driving the recording elements based on an electrical signal from the outside. Also, a portion of the recording element substrate where the recording elements are formed is secured with a ceiling plate formed with a liquid chamber for temporarily storing the ink supplied externally and grooves for constituting the ink flow passages and the ink discharge orifices corresponding to the recording elements. The recording element substrate 101 and the driving element substrate 106 will be described below in succession.
FIGS. 2A and 2B are plan views of the recording element substrate as shown in FIG. 1, and a cross-sectional view thereof taken along the line 2B--2B. As shown in FIGS. 2A and 2B, the recording element substrate 101 has formed thereon an HfB.sub.2 layer 104 which is a heating resistive layer. The HfB.sub.2 layer 104 is connected via pattern wirings 105a, 105b to a common wiring electrode 102b made of aluminum and a plurality of individual wiring electrodes 102a made of aluminum arranged in one row at the end of the recording element substrate 101. On each pattern wiring 105a, 105b and the HfB.sub.2 layer 104, an SiO.sub.2 layer 111 for anti-oxidation and insulation is formed. Further, a Ta layer 112 for anti-cavitation is formed on a portion of the SiO.sub.2 layer 111 over the HfB.sub.2 layer 104, and a photosensitive polyimide layer 113 for ink proof and insulation is formed on the other portion.
FIG. 3 is a plan view of the driving element substrate as shown in FIG. 1. As shown in FIG. 3, the driving element substrate 106 is formed with a plurality of connecting wiring electrodes 109a corresponding to discrete electrodes 102a of the recording element substrate 101 respectively, and two connecting wiring electrodes 109b corresponding to a common wiring electrode 102b of the recording element substrate 101. These connecting wiring electrodes 109a, 109b are arranged in one row and connected to the driving elements 107 respectively. And by joining this driving element substrate 106 with the recording element substrate 101 as shown in FIG. 1, the wiring electrodes 102a are individually connected to the connecting wiring electrodes 109a, and the common wiring electrode 102b is connected to the connecting wiring electrodes 109b.
On the basis of the above-described constitution, if a driving signal from the driving elements 107 is applied via connecting electrodes 109a to the recording element substrate 101, a current will flow through the HfB.sub.2 layer 104, thereby generating heat energy in the HfB.sub.2 layer 104. By the use of this heat energy, the recording can be made on the recording medium. For example, in a thermal head, which is provided with no ceiling plate 153 as shown in FIG. 1, this heat is directly used for the coloring on the thermosensitive paper, or fuse the ink of an ink ribbon for transfer onto the recording medium. Also, in an ink-jet head, a ceiling plate 153 is further secured onto the recording element substrate 101 to form the ink flow passages, as shown in FIG. 1, whereby the recording can take place by discharging the ink within the ink flow passages by means of the heat energy produced in the HfB.sub.2 layer 104.
Normally, a plurality of heating elements (recording elements) composed of a combination of the HfB.sub.2 layer 104, discrete electrodes 102a and pattern wirings 105a, 105b are formed on one recording element substrate 101, as shown in FIG. 2A. Thereby, a recording apparatus for recording plural dots can be obtained, with higher speed of the recording attained. In particular, as the recording of higher density and at higher speed is greatly demanded nowadays, it is common practice that the recording for one main scan line is made at the same time, and accordingly, a recording element unit having arranged a number of heating elements at high density has appeared.
In recording plural dots at the same time by means of a plurality of heating elements arranged on one recording element substrate 101, each of the heating elements must be individually controlled to turn on or off. The driving elements 107 for making such control is normally formed on other substrate than the recording element substrate 101 as above described, with this substrate being connected to the recording element substrate 101, although it can be formed within the recording head substrate 101. This is because where the heating elements and the driving elements 107 are formed on the same substrate, if either the heating elements or the driving elements 107 fail, the other elements will also malfunction.
On the other hand, a technique for securely making the electrical connection between the recording element substrate 191 and the driving element substrate 106 was disclosed in Japanese Laid-open Patent Application No. 3-121851. This technique involves joining the recording element substrate 201 and the driving element substrate (not shown) by pressure welding, with each electrode 202a, 202b of the recording element substrate 201 being of bump shape, as shown in FIGS. 4A and 4B. Thereby, the recording element substrate 201 and the driving element substrate can be securely joined even if they are warped.
Also, a technique using an electrical connecting member was disclosed in Japanese Laid-open Patent Application No. 1-302829. This technique involves joining a recording element substrate 301 and a driving element substrate 306 by pressure bonding with an electrical connecting member 310 carried at a junction between the recording element substrate 301 and the driving element substrate 306, as shown in FIG. 5. Herein, a plurality of electrodes are formed by disposing insulating membranes 303, 308 at respective predetermined pitches on the electrode portions 302, 307 across the surfaces of the recording element substrate 301 and the driving element substrate 306, respectively, as shown in FIGS. 6A and 6B. The electrical connecting member 310 is composed of electrically conductive members 311 and insulating holding members 312 which are alternately disposed. The pitch of electrical conductive members is narrower than that of electrodes, so that the opposed electrodes of the recording element substrate 301 and those of the driving element substrate 306 are securely connected electrically.
On the other hand, it is required that the electrodes of the recording element substrate and the connecting electrodes of the driving element substrate be positioned at high precision with respect to each other, because of their high density arrangement. For the positioning between the recording element substrate and the driving element substrate, a positioning pin may be provided on a holding member for the recording element substrate or a jig to place the end face of the driving element substrate into abutment with this pin, or at least one of the recording element substrate and the driving element substrate is made of a transparent material to enable minute adjustment of the position between the recording element substrate and the driving element substrate, while confirming the position of electrodes with one's own eyes or by means of optical means such as a TV camera.
FIG. 7 is a perspective view of an ink-jet recording apparatus using a recording element unit as shown in FIG. 1. In FIG. 7, a recording element substrate 101 is fixed to a main base board 151, and a driving element substrate 106 is fixed to a sub-base board 152. The sub-base board 152 is pressed via an elastic member 155 by an application plate 154, thereby allowing the recording element substrate 101 and the driving element substrate 106 to be welded by pressure and electrically connected. The recording element substrate 101 is secured to a ceiling plate 153 having formed grooves (not shown) therein for constituting the ink flow passages corresponding to the positions of an HfB.sub.2 layer 104 (see FIGS. 2A and 2B), ink discharge orifices and a common liquid chamber for holding the ink to be supplied to the ink flow passages. The common liquid chamber stores the ink supplied through a filter box 158, an ink supply tube 157 and an ink supply pipe 156 from an ink tank (not shown).
Also, in this ink-jet recording apparatus having the recording element substrate 101 and the driving element substrate 106 which are pressed to each other by the application plate 154, if either of the recording element substrate 101 or the driving element substrate 106 fails, it can be simply replaced.
However, since the wirings and electrodes are arranged at high density as the recording elements are arranged at high density in recent years, it is required that the recording element substrate and the driving element substrate be aligned at high precision. Accordingly, the misregistration which conventionally caused no problem will result in an electrical contact failure in some cases. With the conventional alignment method, it was difficult to attain a sufficient alignment precision corresponding to the high density arrangement of recording elements. In addition, a dedicated jig or tool was required for the alignment between the recording element substrate and the driving element substrate, as previously described.
Thus, an object of the present invention is to provide a recording head which allows the alignment between the recording element substrate and the driving element substrate easily and accurately without the use of any special jig or tool, a recording apparatus using the recording head, and a manufacturing method for the recording head.
To achieve the above-described object, the recording head of the present invention comprises a recording element substrate provided with a plurality of recording elements for recording on a recording medium based on a signal, and a plurality of wiring electrodes electrically connecting to said recording elements respectively, and a driving element substrate provided with a plurality of driving elements for selectively driving said recording elements, and connecting wiring electrodes for sending said signal output from said driving elements to the wiring electrodes on said recording element substrate, upon being connected to wirings of said recording element substrate, wherein the positioning between said recording element substrate and said driving element substrate is made by abutting said recording element substrate against the end face of said driving elements.
Or the recording head of the invention comprises a recording element substrate provided with a plurality of recording elements for recording on a recording medium based on a signal, and a plurality of wiring electrodes electrically connecting to said recording elements respectively, a driving element substrate provided with a plurality of driving elements for selectively driving said recording elements, and connecting wiring electrodes for sending said signal output from said driving elements to the wiring electrodes on said recording element substrate, upon being connected to wirings of said recording element substrate, and a positioning member, mounted on said driving element substrate by flip-chip bonding, for positioning the junction with said recording element substrate, wherein the electrical connection between said recording element substrate and said driving element substrate is made in the state where said recording element substrate is abutted against said positioning member.
Or the recording apparatus of the invention comprises any one of the recording heads as above described, and means for conveying a recording medium to be recorded by a recording head.
The recording head manufacturing method includes the steps of providing a recording element substrate provided with a plurality of recording elements for recording on a recording medium based on a signal, and a plurality of wiring electrodes electrically connecting to said recording elements respectively, providing a plurality of driving elements for selectively driving said recording elements and a positioning member for positioning the junction with said recording element substrate, through a flip-chip bonding process, on a driving element substrate provided with connecting wiring electrodes for sending said signal output from said each driving element to the wiring electrodes on said recording element substrate, upon being connected to wirings of said recording element substrate, wherein the electrical connection between said recording element substrate and said driving element substrate is made in the state where said recording element substrate is abutted against said positioning member.
Of the recording heads of the present invention as above described, a recording head in which the positioning between the recording element substrate and the driving element substrate is made by abutting one end face of the recording element substrate agains the end face of the driving elements can be fabrication at lower costs or with simpler constitution, because there is no need for providing the special positioning member, or the special process of attaching the positioning member. Further, for a recording head in which the positioning member is disposed through the same flip-chip bonding process as that of providing the driving elements on the driving element substrate, there is no need for mounting the positioning member specifically, resulting in simpler process and lower costs, in which the positioning member is provided on the driving element substrate through the same flip-chip bonding process as that of mounting the driving elements on the substrate. Also, the manufacturing method of the head of the present invention allows for the simplification of the process and the reduction of the manufacturing time.